Exploring source routed forwarding in SDN-based WANs

Software-Defined Networking has been gaining increasing attention in both the research and the industry communities. Separating the control and data planes has brought many advantages such as greater control plane programmability, more vendor independence, possibility of network virtualization, lowered operational expenses, etc. SDN deployments are possible in a variety of contexts: Enterprise networks, WANs and networks connecting data centers. The realization and operation of an SDN requires the inclusion of a central controller. SDN however raises several concerns for WANs including performance limitations due to the larger propagation delays of control information to and from the controller, the increased work load due to a larger number of network elements and concerns as to performance impacts related to the controller placement. This paper attempts to address some of these issues by examining the effects of using source routing as an alternative to hop by hop in an Internet2 SDN-based WAN production deployment. Our analysis shows that source routing can bring significant gains in SDN convergence performance in WAN environments and reduce the sensitivity in performance due to controller placement.